isn't that fun?
so, here' the deal. Oranges don't wanna be eaten by bugs. so they've got stuff in their peels to keep em away. kinda a natural pesticide. it's an oil, and it's flammable, so when you squeeze a peel in half real fast next to a flame (a candle works fine, btw
), you see the oil burn.
http://www.floridachemical.com/whatisd-limonene.htm
that's the stuff.